function plus() {
			var cena = document.getElementById("cena");
			var col = document.getElementById("col");
			var opacityPrice = document.getElementById("opacityPrice");

			col.innerHTML = 1 + Number(col.innerHTML);
			cena.innerHTML = Number(opacityPrice.innerHTML) * Number(col.innerHTML);
		}
		function minus() {
			var cena = document.getElementById("cena");
			var col = document.getElementById("col");
			var opacityPrice = document.getElementById("opacityPrice");

			if (col.innerHTML != "1") {
				col.innerHTML = Number(col.innerHTML) - 1;
				cena.innerHTML = Number(cena.innerHTML) - Number(opacityPrice.innerHTML);
			}
		}

